Fuel additive

ABSTRACT

There is described a fuel additive composition comprising an alkanolamide, an alkoxylated alcohol, an alkoxylated fatty acid, or a derivative thereof, in which the degree of alkoxylation of the C 18  to C 22  fatty acid is from 0.5 to 5 mols of alkoxylate to 1 mol of fatty acid. There is also described a fuel composition comprising a liquid hydrocarbon fuel and a surfactant composition according to the invention. A method of running an internal combustion engine comprising the use of such a fuel is also described.

[0001] This invention relates to novel fuel compositions which comprise novel surfactant compositions and to methods of preparation the fuels compositions and surfactants.

[0002] International Patent Application No WO 98/17745 describes a surfactant composition which comprises,

[0003] 25% v/v of a diethanolamide,

[0004] 50% v/v of an ethoxylated alcohol, and

[0005] 25% v/v of a fourteen carbon chain fatty acid with seven ethoxylate groups.

[0006] WO '745 especially describes fuel compositions comprising, inter alia, an additive made up of a fatty acid diethanolamide, an alcohol ethoxylate and an ethoxylate of a fatty acid, the degree of ethoxylation being selected so that a long term stable fuel composition is formed.

[0007] Specifically, WO '745 teaches the use of lauric acid and lauric diethanolamide.

[0008] Co-pending International Patent Application No WO 99/20715 to Pure Energy Corporation describes similar surfactant compositions in which the fatty acid used has a hydrocarbon chain length of from C₉ to C₁₅.

[0009] Furthermore, U.S. Pat. No. 6,017,369 describes a diesel fuel composition comprising, inter alia, diesel, ethanol and a fatty acid having a carbon chain length of from C₉ to C₁₅.

[0010] Whilst such additives provide significant reductions in emissions and may be useable at low concentrations, they suffer from the disadvantage that, for example, lauric acid has a relatively high melting point of between 44 and 46° C. Thus, at room temperature, lauric acid is waxy and difficult to formulate.

[0011] We have now surprisingly found a novel surfactant fuel additive which overcomes or mitigates the problems of known prior art composition.

[0012] Thus according to the invention we provide a fuel additive composition comprising an alkanolamide, an alkoxylated alcohol and an alkoxylated C₁₈-C₂₂ fatty acid or a derivative thereof in which the degree of alkoxylation of the fatty acid is from 0.5 to 5 mols of alkoxylate to 1 mol of oleic acid.

[0013] The alkanolamide is preferably an ethanolamide and more preferably a diethanolamide. Especially preferred are the diethanolamides and particularly the super diethanolamides. By the term super diethanolamide we mean a diethanolamide in which the nitrogen is substituted by an alkyl substituent e.g. alkyl C₅ to C₂₀, preferably C₈ to C₁₈, more preferably C₁₀ to C₁₈. The most preferred diethanolamide has a C₁₈ alkyl substituent i.e. oleic diethanolamide.

[0014] There are three commercial routes to alkanolamides;

[0015] Acid+alkanolamine=alkanolamide+water

[0016] Plant or animal oil (triglyceride)+alkanolamine=alkanolamide+glycerol

[0017] Methyl ester+alkanolamine=alkanolamide+methanol

[0018] These are listed in order of increasing product quality. The route via the acid often uses an excess of alkanolamine to produce a product higher in amide than is obtainable from the acid if a stoichiometric ratio is used; these products are sometimes referred to as Kritchevsicy amides. The products derived from reaction of substantially stoichiometric proportions of an alkanolamide with a fatty acid ester, typically a methyl or glyceryl ester, are referred to as super amides.

[0019] The alkoxylated alcohol is preferably an ethoxylated alcohol. It is essential that the ethoxylated alcohol is an oil soluble alcohol. Therefore, alkanols are preferred and these may be primary, secondary or tertiary alkanols and especially primary alkanols. As the oil solubility of the alcohol may vary with the carbon chain length of the ethoxylated alkanol, the allcanol is preferably a C₅ to C₂₂ alkanol, more preferably C₅ to C₁₅ alkanol. The ethoxylated alcohol may comprise a mixture of alkanols. However, it is preferred that in such mixtures one alkanol will predominate. Thus, the most preferred alkanol is predominantly a C₉ to C₁₁ alkanol. In addition the degree of ethoxylation of the alcohol may be varied and the oil solubility will, generally, decrease with the increase in the degree of ethoxylation. It is preferred that the ethoxylate to alcohol ratio is greater than 2. More preferably, the ethoxylate to alcohol ratio is from between 1 and 10, preferably between 1 and 5, more preferably between 1 and 3 and especially between 2 and 3. A commercially available ethoxylated alcohol is especially preferred in which the ethoxylate to alcohol ratio is 2.75. Such an alcohol ethoxylate is available as NEODOL 91/2.5.

[0020] The fatty acid ethoxylate may comprise the free acid, an ester, a mixture of esters or a mixture of the acid and one or more esters. When a fatty acid ester ethoxylate is used, the ester is preferably an alkyl oleate, preferably a C₁ to C₁₀ alkyl oleate, such as ethyl oleate and especially methyl oleate. The fatty acid derivative is preferentially an ester which may comprise any conventionally known ester moiety, however, preferably the ester is an alkyl ester. The alkyl group may be a primary, secondary or tertiary alkyl group. However, the preferred ester group is a straight chain alkyl group, the allyl chain being from C₁ to C₁₀. The methyl ester is especially preferred.

[0021] The fatty acid group may be any known C₁₈ to C₂₂ fatty acid but oleic acid (C₁₈) is preferred.

[0022] Alkyl ester fatty acid ethoxylate may be manufactured using conventional methods known per se. However, current technology only permits ethoxylation of a fatty acid ester by the PEG/fatty acid route where, in a fatty acid of the general formula RCOOR¹, R¹ is methyl.

[0023] We have now found that such ethoxylated fatty acid esters may be manufactured by esterification of a fatty acid with a methoxy polyethylene glycol (PEG) or any other alcohol ethoxylate, for example, a C₉ or C₁₁ alcohol ethoxylate.

[0024] Such novel processes can produce ethoxylated fatty acid esters of the general formula;

RCO[CH₂CH₂O]_(n)OR¹  I

[0025] wherein R is an alkyl C₈ to C₂₀ group;

[0026] R¹ is an alkyl, C₁ to C₁₀; and

[0027] n is an integer from 1 to 10.

[0028] Alternatively, ethoxylated fatty acids of formula I may be manufactured by esterification of RCOOH with R¹[OCH₂CH₂]_(n)OH, wherein R, R¹ and n have the meanings defined above.

[0029] However, in addition, the alcohol ethoxylate might be, for example, an alkylphenol ethoxylate.

[0030] The degree of alkoxylation, e.g., ethoxylation, propyloxylation or a mixture thereof, is chosen to optimise performance in the blend with the other two selected surfactants and may be from 0.5 to 5 but more preferably from 0.5 to 2.5. It is especially preferred that the alkoxylation comprises ethoxylation. A suitable product within this range would be, for example that derived from the addition of 1 mol of ethylene oxide to 1 mol of oleic acid, or a derivative thereof.

[0031] The fatty acid ethoxylate, e.g. oleic acid ethoxylate, may be derived from a variety of feedstocks, readily available worldwide. However, in a preferred embodiment of the invention the fatty acid ethoxylate may be produced by ethoxylation or esterification of acids derived from animal fats e.g. beef tallow or vegetable oils, such as soya, etc.

[0032] Thus the oleic acid precursor may be predominantly, e.g. from 65-70% v/v, fatty acid, e.g. oleic acid, but may also contain linoleic acid, e.g., 10-12% v/v, and may also include small amounts of stearic, palmitic and/or myristic acids.

[0033] The ratio of the fatty acid alkoxylate, e.g. oleic acid alkoxylate to the alkanolamide may vary slightly, but is preferably 1:1 v/v.

[0034] The additive of the invention may be added to any known hydrocarbon fuel, e.g. diesel, petrol or alcohol, such as ethanol, which may or may not contain water. The invention is seen to particularly good effect when added to fuels based on low fraction oils.

[0035] The preferred additive of this invention is a non-ionic surfactant and preferably a blend of surfactants. It is a preferred feature of this invention that the surfactants be selected by their nature and concentration that the additive (as well as any water or other non-fuel liquid present) be solubilised within the fuel. For this purpose it is convenient to have regard to the hydrophilic-lipophilic balance (HLB) of the surfactant, the value being calculated according to the expression. ${HLB} = \frac{{{mol}.\quad {wt}}\quad {of}\quad {hydrophilic}\quad {chain} \times 20}{{total}\quad {{mol}.\quad {wt}}}$

[0036] The values will depend on the length of the hydrophilic chain, typically an ethoxylate chain. The length of the chain will increase the extent of solubilisation because of a greater ability to solubilise.

[0037] As with the compositions described in WO98/17745, a blend of surfactants is preferred, preferably by selecting one appropriate to the fuel.

[0038] The invention has the ability to unify the HLB requirements of any liquid fuel which in turn allows for one dose to be used in any fuel from C5 carbon chains up. The benefit being the amount of treatment directly related to the co-solvency ability.

[0039] Preferably the ethoxylate of the oleic acid makes up about 25% by volume of the additive and further preferably the alcohol ethoxylate comprises 50% by volume of the additive.

[0040] An additive of the invention may be added to a hydrocarbon fuel, eg diesel, petrol or alcohol, such as ethanol which may or may not be contaminated with water. Alternatively the hydrocarbon fuel may be a blend of a petroleum based fuel such as diesel or petrol, with an alcohol such as ethanol. The invention is seen to particularly good effect when added to synthetic fuels based on low fraction oils.

[0041] The hydrocarbon fuel may comprise any known hydrocarbon fuel or mixtures thereof, therefore such fuels include but shall not be limited to diesel, e.g., petroleum diesel, gasoline, aviation fuel, alcohol, etc.

[0042] In one embodiment of the fuel composition of the invention the hydrocarbon fuel is a petroleum diesel fuel. Such fuels may generally be obtained from the distillation of petroleum and its efficiency can be measured by the cetane number. Suitable diesel fuels for use in accordance with the invention generally have a cetane number of from 35 to 60, preferably from 40 to 50. The amount of diesel fuel blended to form the fuel composition of the invention may be from 60% v/v to 95% v/v, based on the total volume of the fuel consumption.

[0043] In a further feature of the invention the hydrocarbon fuel, such a diesel or gasoline may include an amount of an oxygenator, e.g. alcohol, an alkanol, such as ethanol. When an alcohol is present the amount of alcohol may vary depending, inter alia, upon the nature of the fuel, but may in an amount of from 1 to 50% v/v, preferably 5 to 20% v/v.

[0044] For fuels, ethanol may be produced from fossil fuel feedstocks or by fermentation of sugars derived from grains or other biomass materials. Therefore, ethanol suitable for use in accordance with the fuel compositions of the invention may be fuel grade ethanol derived from yeast or bacterial fermentation of starch-based sugars. Such starch-based sugars may be extracted from corn, sugarcane, tapioca and sugar beet. Alternatively, fuel grade ethanol may be produced via known dilute and/or concentrated acid and/or enzymatic hydrolysis of a particular biomass material, for example, from waste industrial sources including, cellulosic portions of municipal solid waste, waste paper, paper sludge, saw dust. Biomass may also be collected from agricultural residues including, for example, rice husks and paper-mill sludge.

[0045] A suitable fuel grade ethanol for use in accordance with the invention may contain none or only contaminant levels of water. Alternatively, a suitable fuel grade ethanol for use in accordance with the invention may contain higher amounts of water, up to 5% w/w (hydrous ethanol).

[0046] Use of ethanol in combination with a diesel fuel has previously posed problems wherein the ethanol/diesel fuel mixture would undesirably separate into two distinct phases, especially when water is present, and render the resultant mixture unsuitable for use as a combustible fuel. The use of the fuel additives of the invention permits hydrous ethanol to be blended satisfactorily with conventional diesel fuel without forming two phases. The use of fuel grade ethanol blended in accordance with the invention imparts desirable combustion characteristics to the overall fuel composition; such as improved fuel stability, lower smoke and particulate matter, lower CO and NOx emissions, improved antiknock characteristics, and/or improved anti-freeze characteristics.

[0047] In another aspect the invention provides a fuel composition comprising a light weight fraction and a surfactant fuel additive as hereinbefore described.

[0048] The presence of the additive of the invention ensures that the fuel composition forms a consistent stable homogenous composition and creates a monolayer simultaneously a result of which leads to a better more complete burn which reduces pollution and increases miles per gallon.

[0049] As a result a blended fuel, particularly alcohol based, is able to combust more precisely with a cooler charge to reduce the iron-formates present from the aldehyde peracids and peroxide reactions normally attributable to engine degradation.

[0050] Thus we further provide a fuel composition comprising a fuel and a hydrocarbon fuel additive as herein before described.

[0051] The concentration of the additive in such fuel compositions can be very low, typically of the order of 0.5-50:1000 v/v, preferably from about 1:1000 to 30:1000 v/v and most preferably from 1 to 3:100 v/v. There appears to be no technical or economic benefit in adding more unless a co-solvent dual action is required, when the priority will be dosage against performance. However, the additive to fuel ratio may vary depending upon, inter alia, the nature of the fuel. Thus, for example, when the fuel is a hydrous ethanol/diesel blend, the additive to fuel ratio may be as much as 5% v/v, e.g. from 0.1 to 5% v/v, more preferably from 1 to 3% v/v. Alternatively, when the fuel is an anhydrous ethanol/diesel blend the additive to fuel ratio may be as much as 3% v/v, e.g. from 0.1 to 3% v/v. The amount of ethanol present in the diesel/ethanol blends of the invention may be from 5 to 25% v/v, preferably from 7 to 10% v/v and especially 7.7% v/v. When the ethanol in the blend is hydrous ethanol, the amount of water present may be from 4 to 6% v/v based as a percentage of the ethanol.

[0052] Alternatively, when the fuel is gasoline or a gasoline/ethariol blend, then the additive to fuel ratio may be as much as 5% v/v, from 0.1 to 5% v/v, preferably up to 3% v/v, e.g. 0.1 to 3% v/v, more preferably from 1 to 3% v/v. The amount of ethanol present in the gasoline/ethanol blends of the invention may be from 1 to 25% v/v, preferably 5 to 25% v/v, more preferably from 7 to 10% v/v and especially 7.7% v/v. When the fuel is a hydrous ethanol/gasoline blend, the additive to fuel ratio may be as much as 5% v/v. Alternatively, when the fuel is an anhydrous ethanol/gasoline blend the additive to fuel ratio may be as much as 3% v/v.

[0053] The presence of the additive of the invention ensures that the fuel composition forms a consistent stable homogenous composition and creates a monolayer simultaneously a result of which leads to a better more complete burn which reduces pollution and increases miles per gallon.

[0054] As a result a blended fuel, particularly alcohol based, is able to combust more precisely with a cooler charge to reduce the iron-formates present from the aldehyde peracids and peroxide reactions normally attributable to engine degradation.

[0055] We also provide a method of running an engine adapted to use a hydrocarbon or an alcohol based fuel which comprises the use of a fuel composition as hereinbefore described.

[0056] The use of a fuel additive composition comprising an oleic acid ethoxylate or a derivative thereof is especially advantageous in conjunction with diesel fuel compositions and especially diesel/alcohol compositions. Thus, according to a further feature of the invention we provide a fuel composition comprising a diesel fuel, an alcohol and a surfactant additive as hereinbefore described.

[0057] The alcohol is preferably ethanol. Optionally, the diesel composition of the invention may additionally include the use of an alkyl ester of oleic acid e.g. an alkyl C1 to 6 alcohol or a long chain fatty alcohol and, optionally a co-solvent of an alkyl alcohol, e.g. a C₃ to C₆ alcohol.

[0058] According to a further feature of the invention we provide the use of oleic acid or a derivative thereof in the manufacture of a surfactant additive as hereinbefore described.

[0059] According to a yet further feature of the invention we provide the use of oleic acid or a derivative thereof in the manufacture of a fuel composition as hereinbefore described.

[0060] The invention will now be described by way of example only.

EXAMPLE 1 Emission Tests

[0061] Emission tests were carried out on a fuel composition containing the 95% diesel 5% ethanol blend and AAE01.

[0062] AAE01 is a surfactant composition comprising 25% v/v of oleic diethanolamide, 50% v/v of NEODOL 91/2.5, and 25% v/v of oleic acid with one molar equivalent ethoxylate groups.

[0063] 1.1 Test Engine

[0064] General features of the test engine are given in Table 1. TABLE 1 General features of the test engine. Make, model VOLVO DH10A-285 Number of cylinders and lay-out 6, in-line Displacement 9.6 dm³ Injection pump electrically controlled mechanical in-line pump Maximum power output 210 kW at 2000 l/min Maximum torque 1200 Nm at 1450 l/min Compression ratio 20:1 Combustion system direct injection, turbocharged, intercooled Emission level Euro II

[0065] 1.2 Test Equipment and Procedures

[0066] All equipment used for measuring the regulated emissions (Co, Hc, Nox and particulates) conform with the specifications for measurement system given in Annex 4 of ECE Regulation No 49/02.

[0067] A hydraulic dynamometer by Zollner and a “PUMA Test Assistant” control system by AVL were used for running and controlling the test engine. Regulated gaseous emissions were measured with analysis system by BOO Instrument AB. Particulates were collected using AVL Mini Dilution Tunnel 474. Particulate filters used were Pallflex TXH120WW φ 70 mm filters.

[0068] Test procedure was 13 mode test according to ECE Regulation No. 49/02. The maximum power output obtained with each fuel was used to set dynamometer load setting.

[0069] The tests were carried out at normal test temperature.

[0070] FTIR Measurement, Formaldehyde from Heavy-Duty Engine

[0071] In the heavy-duty engine tests, a number of unregulated compounds, including formaldehyde, were measured using a Fourier Transformation Infra-Red (FTIR) system (SESAM II Fast, manufactured by Siemens AG, FRG). More than 20 exhaust components can be measaured with this system at a one second time interval.

[0072] 1.3 Test Results

[0073] The maximum power obtained with D1 fuel wasa 210 kW at 2000 rpm and maximum torque 1200 Nm at 1450 rpm. Power loss with fuel D2 was below 1% when compared to D1 fuel. Power losses with fuels D3 and D4 when compared to D1 fuel were 5 and 7% respectively.

[0074] Results of the emission tests according to the ECE R49 13-mode test for heavy-duty tests are given in Table 2. One test with each fuel was carried out.

[0075] Increase in HC emission was observed for fuels D3 and D4 when compared to fuel D1.

[0076] NO_(x) emission seemed to be slightly lower with fuels D2, D3 and D4 than with fuel D1. However, the change lower than 5% cannot be regarded as very significant due to uncertainty of the measurement method.

[0077] Particulate matter emission was about 11% lower with D2 fuel than with D1 fuel. D3 fuel resulted 20% and D4 fuel 27% lower particulate emission than D1 fuel. Also black smoke (Bosch smoke) seemed to be lower with fuels D2, D3 and D4 when compared to D1 fuel. TABLE 2 Results of the emissions tests according to ECE R49 test procedure with the VOLVO DH10A-285 engine CO HC NO_(x) Particulates CO₂ Fuel cons. Bosch Fuel (g/kWh) (g/kWh) (g/kWh) (g/kWh) (g/kWh) (g/kWh) smoke* D1 (Base) 0.51 0.15 6.3 0.105 688 230 0.50 D2 (Base + 0.51 0.15 6.2 0.093 693 231 0.48 2% AAE01) D3 (Base + 0.51 0.20 6.1 0.084 696 233 0.41 2% AAE01 + 2% H₂O) D4 (Base + 0.51 0.20 6.0 0.076 698 235 0.40 1% AAE01 + 5% MTBE)

[0078] The results of FTIR measurements are shown in Table 3. The most components measured from the exhaust gases of Volvo DH10A-285 engine were below the detection limit of FTIR equipment. Formaldehyde emission seemed to be slightly higher with D3 fuel than with D2 fuel. The difference resulted from the high load modes 6 and 8. The emission of n-octane was higher with D3 fuel than with D2 fuel, which is in accordance with the results of regulated emissions shown in Table 2. TABLE 3 Results of the FTIR measurements from ECE R49 test with the VOLVO DH10A-285 engine. N₂O (mg/ NH₃ CH₂O CH₄ BNZ NC₈ Fuel kWh) (mg/kWh) (mg/kWh) (mg/kWh) (mg/Kwh) (mg/kWh) D2 bd bd 24 bd bd  97 D3 bd bd 35 BD BD 120

EXAMPLE 2 Light-Duty Emission Tests

[0079] 2.1 Test Vehicle

[0080] The general features of the petrol fuelled vehicle that was used in the emission tests are shown in Table 4. TABLE 4 General features of the test vehicle Make, model Ford Mondeo 1.6 BFP/270 Model year 1998 Odometer reading 29 100 km Transmission manual, 5 Number of cylinders and lay-out 4 Displacaement 1.6 dm³ Maximum power output 66 kW

[0081] The absolute emission level obtained with FTIR equipment may vary significantly from the level obtained with traditional measurement technologies. However, FTIR technology can be used for comparison of the results with different fuels. Due to very low level hydrocarbon emissions from diesel engines, the most compounds that can be measured with FTIR equipment are beloe the detection limit. When diesel engines are considered, FTIR is most suitable to monitor the formaldehyde emission. Examples of the compounds that were recorded during these measurements were as follows:

[0082] formaldehyde (CH₂O)

[0083] nitrogen dioxide (NO₂)

[0084] nitrous oxide (N₂O)

[0085] ammonium (NH₃)

[0086] methane (CH₄)

[0087] ethyne (C₂H₂)

[0088] ethene (C₂H40

[0089] propene (C₃H₆)

[0090] benzene (BNZ)

[0091] n-octane (NC₈)

[0092] 1,3-butadiene (C₄H₆)

[0093] Test Equipment and Procedures

[0094] All equipment usd for exhaust dilution and collection, as well as concentration analysis of the gaseous regulated emissions, conform with the specificatioins of the Amendment 91/441/EEC of Directive 70/220/EEC.

[0095] A DC type chassis dynamometer manufactured by Froude Consine and an emission measaurement system by Pierburg GimbH (FRG) were used,

[0096] Tests were conducted at normal test temperature (+23° C.). The vehicle was preconditioned with running three times the EUDC part of the test, and soaked at the test temperature for 12 to 16 hours before the test.

[0097] The chassis dynamaometer settings used for vehicle are presented in Table 5. TABLE 5 Chassis dynamometer settings Inertia 1360 kg F₀ 7 F₁ 0 F₂ 0.046

[0098] The gaseous regulated emissions were divided into three sub-cycles. The first part included the first two individual sub-cycles of urban cycle, ECE15 (marked as Phase 1), the second phase was the rest of the ECE15 cycle. (marked as Phase 2), and the third part was the extra urban portion (marked as Phase 3) of the current European test cycle (marked as 91/441/EEC).

[0099] The results of the test were compared by Sekab with results obtained from similar tests carried out by a AB Svensk Biprovning Motocenter (Swedish Engine and MOT test centre) on several fuel compositions including Swedish Mk1 diesel, generally regarded as the cleanest diesel available in Europe.

[0100] The comparisons shown on the Bi07/Ethanol/Diesel Emission Test Results are evidence to a dramatic reduction in all measured emissions including, −20% CO₂, −30% NO_(x) and −70% particulates.

[0101] Five months after the original tests VTT took the sample of fuel they had been keeping and ran a cetane test on it, the result of which is enclosed. As noted in this test the sample had remained clear and stable for this period and no deterioration was evident.

[0102] Results CO HC Nox CO2 Particulates g/kWh g/kWh g/kWh g/kWh g/kWh AAE01/Ethanol/Diesel Blends Emission Test Results Mk1  0.61  0.47  6.95 1085  0.2 Mk2  0.61  0.5  7.14 1053  0.21 RME  0.49  0.09  8.99 1053  0.21 Mk1 + 5% RME  0.62  0.44  7.16 1054  0.2 Mk2 + 30% RME  0.58  0.33  7.8 1068  0.19 AAE01 Diesohol  0.55  0.21  4.9  863.6  0.056 AAE01 diesohol compared with Mk1 diesel Mk1 Diesel  0.61  0.47  6.95 1085  0.2 AAE01 Diesohol  0.55  0.21  4.9  863.6  0.056 Reductions 10% 55% 29%  20% 72%

[0103] All testing carried out on a Volvo Euro II low emission engine. 

1. A fuel additive composition comprising an alkanolamide, an alkoxylated alcohol, an alkoxylated C₁₈ to C₂₂ fatty acid, or a derivative thereof, in which the degree of alkoxylation of the fatty acid is from 0.5 to 5 mols of alkoxylate to 1 mol of fatty acid.
 2. A fuel additive composition according to claim 1 characterised in that the alkanolamide is an ethanolamide
 3. A fuel additive composition according to claim 3 characterised in that the alkanolamide is a diethanolamide.
 4. A fuel additive composition according to claim 3 characterised in that the diethanolamides are super diethanolamides.
 5. A fuel additive composition according to claim 3 characterised in that the nitrogen in the diethanolamide is substituted by an alkyl C₅ to C₂₀ substituent.
 6. A fuel additive composition according to claim 5 characterised in that the diethanolamide is substituted by an allyl C₈ to C₁₈ substituent.
 7. A fuel additive composition according to claim 6 characterised in that the diethanolamide is substituted by an alkyl C₁₀ to C₁₈ substituent.
 8. A fuel additive composition according to claim 7 characterised in that the diethanolamide is oleic diethanolamide.
 9. A fuel additive composition according to claim 1 characterised in that the alkoxylated alcohol is an ethoxylated alcohol.
 10. A fuel additive composition according to claim 9 characterised in that the ethoxylated alcohol is an oil soluble alcohol.
 11. A fuel additive composition according to claim 9 characterised in that the ethoxylated alcohol is an alkanol.
 12. A fuel additive composition according to claim 11 characterised in that the ethoxylated alcohol is a primary alkanol.
 13. A fuel additive composition according to claim 11 characterised in that the alkanol is C₅ to C₂₂ alkanol.
 14. A fuel additive composition according to claim 11 characterised in that the ethoxylated alcohol comprises a mixture of alkanols in which one allcanol predominates.
 15. A fuel additive composition according to claim 11 characterised in that the predominant alkanol is a C₉ to C₁₁ alkanol.
 16. A fuel additive composition according to claim 9 characterised in that the ethoxylate to alcohol ratio is from between 1 and
 10. 17. A fuel additive composition according to claim 16 characterised in that the ethoxylate to alcohol ratio is from between 1 and
 5. 18. A fuel additive composition according to claim 17 characterised in that the ethoxylate to alcohol ratio is from between 2 and
 3. 19. A fuel additive composition according to claim 18 characterised in that the ethoxylate to alcohol ratio is 2.75.
 20. A fuel additive composition according to claim 19 characterised in that the ethoxylated alcohol is NEODOL 91/2.5.
 21. A fuel additive composition according to claim 1 characterised in that the fatty acid derivative is present as the free acid.
 22. A fuel additive composition according to claim 1 characterised in that the fatty acid is present as oleic acid, or a derivative thereof.
 23. A fuel additive composition according to claim 22 characterised in that the oleate is an alkyl oleate
 24. A fuel additive composition according to claim 23 characterised in that the oleate is an alkyl oleate.
 25. A fuel additive composition according to claim 1 characterised in that the degree of alkoxylation is
 1. 26. A fuel additive composition according to claim 1 characterised in that the composition comprises 25% v/v of the oleic acid ethoxylate or a derivative thereof.
 27. A fuel additive composition according to claim 1 characterised in that the composition comprises 50% v/v of the alcohol ethoxylate.
 28. A fuel composition comprising a liquid hydrocarbon fuel and a fuel additive composition according to claim
 1. 29. A fuel composition according to claim 28 characterised in that the fuel is a diesel fuel.
 30. A fuel composition according to claim 29 characterised in that the fuel is a mixture of diesel and an alcohol.
 31. A fuel composition according to claim 30 characterised in that the alcohol is ethanol.
 32. A fuel composition according to claim 28 characterised in that the fuel additive to fuel ratio is from 0.5-50:1000 v/v.
 33. A fuel composition according to claim 32 characterised in that the fuel additive to fuel ratio is from 1:1000 to 30:1000 v/v
 34. A fuel composition according to claim 33 characterised in that the fuel additive to fuel ratio is from 1 to 3:100 v/v.
 35. A fuel composition according to claim 31 characterised in that the fuel is a hydrous ethanol/diesel blend.
 36. A fuel composition according to claim 35 characterised in that the additive to fuel ratio is up to 5% v/v.
 37. A fuel composition according to claim 31 characterised in that the fuel is an anhydrous ethanol/diesel blend.
 38. A fuel composition according to claim 37 characterised in that the additive to fuel ratio is up to 3% v/v.
 39. A fuel composition according to claim 28 characterised in that the fuel is gasoline.
 40. A fuel composition according to either of claim 39 characterised in that the fuel is gasoline/ethanol blend.
 41. A fuel composition according to claim 39 characterised in that the additive to fuel ratio is up to 5% v/v.
 42. A method of running an internal combustion engine comprising the use of a fuel according to claim
 28. 43. The use of a C₁₈ to C₂₂ fatty acid, or a derivative thereof, in the manufacture of a fuel additive composition according to claim
 1. 44. The use according to claim 43 characterised in that the C₁₈ to C₂₂ fatty acid is oleic acid, or a derivative thereof.
 45. The use of a C₁₈ to C₂₂ fatty acid, or a derivative thereof, in the manufacture of a fuel composition according to claim
 28. 46. The use according to claim 45 characterised in that the C₁₈ to C₂₂ fatty acid is oleic acid, or a derivative thereof.
 47. A fuel additive or a fuel composition substantially as described in the accompanying examples. 